Multiplex transmission system



jun@ 30, 1936. E. T. BUFToN MULTIPLEX TRANSMISSION SYSTEM Filed Feb. 9, 1954 4 Sheets-Sheet l 'June 30?' 1936- E. T. BURTON n MULTIPLEX TRANSMISSION SYSTEM /NVE/VTOR 27T/BURTON By y g 4 Sheets-Shee-t 2 Filed Feb. 9, 1954 A TTORNEV June 30, 1936- E. T, BURTON MULTIPLEX TRANSMISSION SYSTEM EEEWL E@ @Fgt VQMLrML-w IW Filed Feb. 9, 1934 ATTORNEY Juize 30, 1936. E. T. BURTON MULTIPLEX TRANSMISSION SYSTEM Filed Feb. 9', 1934 TL Sheets-Sheet 4 @Y a MW,

AT TOR/VE V Patented June 30, 1936 UNETED STATES PATENT OFFIQE MULTIPLEX TRANSMISSION SYSTEM Everett T. Burton, Millburn, N.

Bell Telephone Laboratories,

J., assignor to Incorporated,

1i) Claims.

This invention relates to impulse transmission systems and particularly to circuits for enabling multiplex telegraph line sections of respectively different channel capacities to operate in tandem.

It is frequently desirable to so connect a slow speed line section as, for example, a submarine cable to a high speed line section such as a telegraph land line that messages may be transferred or repeated from one to the other by automatic repeating apparatus thus enabling through transmission to be had over the sections operating in tandem. This, although enabling direct transmission without the repetition of the message by an operator at the repeating. station, is wasteful of plant facilities in that it effectively restricts the message transmission capacity of the higher speed section to that oi the lower speed section.

An object of the invention is to connect high speed and low speed line sections for automatic repeating operation, one to the other, without sacrificing the additional transmission capacity inherent in the higher speed section.

An additional object of the invention is to enable interconnection of two rotary distributor Baudot telegraph systems having respectively different numbers of channels to enable as many channels of the fewer channel system as desired to be associated with corresponding channels of the higher channel system without sacrifice of the excess channel capacity of the latter.

In accordance with the invention a low speed section is connected to a high speed section by repeating apparatus comprising mechanically associated rotary distributors. The distributor associated with the low speed section has fewer channels and hence fewer segments than that associated with the high speed section. The transmitting and receiving segments of the low speed section are connected by means of groups of storage elements to a similar number of receiving and transmitting segments of the high speed section. By properly choosing the munber of storage elements and by correctly phasing the operations of storing, retransmitting from the storage elements and clearing the storage elements it is possible to enable one-way at a time transmission between the line sections without mutilation of signals. It is, moreover, possible to accomplish this with storage elements fewer in number than the aggregate number of impulses to be stored during one cycle of the distributor associated with the low speed section. The excess message capacity of the high speed section represented by those channels which are not repeated to the low speed section may be utilized by diverting those channels at the repeating station into local apparatus or separate circuits terminating locally or into a second low speed section.v Y

In ari-alternative arrangement a single high speed section may be similarly associated at a repeating point with two low speed sections to each of which a portion of its message capacity is assigned.

The invention may best be understood by reference to the following description when read in connection with the annexed drawings in which:

Fig. i is a schematic diagram of a portion of a rotary distributor repeating apparatus to assist in explaining the operation of repeating impulses oi a plurality of signal channels from a high speed transmission line to a low speed transmission line;

Figs. 2 and 3 are similar diagrams relating to repeating from the low speed section to the high speed section;

Fig. l illustrates schematically the apparatus employed at a rotary distributor repeating station for repeating four through channels from a high speed section to a low speed section together with two local drop-off channels;

Fig. 5 shows the corresponding apparatus for repeating in the reverse direction at the repeater station of Fig. 4; and,

Fig. 6 illustrates a modification of a portion of the apparatus of Fig. 4 in which a single dropo channel is employed.

Referring to Fig. 1, a high speed section l having a large message capacity is associated with a low speed section 2 by rotary distributor repeating apparatus to repeat impulses from section l to section 2 for the through channel and to repeat impulses from section l to local printing circuits for the drop-oli channel. Section I serves to impress received impulses upon a storing' brush 3 which moves toward the right traversing the segments of a high speed distributor ring A. Segments A1, Az-AX are allotted to impulses of the through channel to be repeated to section 2 and segments C1, C2, C3 are allotted to the impulses of the drop-off channel`which are repeated to the locally terminated channel apparatus. A low speed distributor ring on the same distributor is provided with segments B1, Bz-Bx which receive impulses repeated respectively from segments A1, A2, etc. A transmitting brush fi which moves to the right traverses the segments on the low speed distributor ring to transmit the repeated impulses to the low speed section 2.

Assume that the C segments are each equal in length to the A segments and that the number n oi C segments in the consecutive groups C1, C2, etc. is small. In order to ascertain the minimum numberl of storage relays which is required we may start with the fact that each segment on which the storage brush has impressed an impulse to be repeated requires a storage relay to hold the stored impulse until it can be retransmitted to section 2. Asthe storage brush proceeds, one

Vstorage relay after another will come into operation and must be maintained operated untii it has retransmitted its impulse to the second sec; tion after which it may be cleared or restored to normal unenergized condition. If retransmission to the line section 2 is eiected at the earliest pos sible moment after storage andif itis followed g immediately by restoring or clearingthe segments of any remanent charge the number of necessary storage relays will be measured by the number of segments between the storing brush and the restoring brush. Y l

It isevident that when transmitting brush 4 has just completed transmission from the seg- Yment BX, or in other words, is at the position indicated by the dotted line o the restoring brush 5 associated with the segments of the high speed ring A must lag behind brush 4 by a distance corresponding to 'nC segments plus the Axsegment since brush 5 must not interferewith the energized condition of AX until after brush 4 has transmitted to section 2 an impulse of BX which corresponds to the energization of A11.v Accordingly, when brush rl is at position o brush 5 can not be farther advanced in its travel than the initial edge of Ax. .Y

It is also evident that before transmitting brush Il advances beyond the dotted line o at which it is ready to begin transmitting an impulse fromV segment B1 to: the low speed section 2, storing brush 3 must have passed beyond segment A1 so that the impulse received by A1 from the high speed'section has been fully stored and so that segment B1 has been properly conditioned by that stored impulse. In other words, when brush 4 is at Yline o storing brush 3 must have completelyv traversed segment A1 or be one A section in advance of line o.V It will accordingly be Yapparent that the minimum separation of the storing brush 3 and the restoring brush 5 nC segments plus two A segments, or if the high speed C and A segments are equal in length the spacing in terms thereof is n+2. The number of relays must be such that there will be one relay ready to begin storing just as another has been cleared by the restoring brush or one greater than the minimum spacing between the storing and restoring brushe Accordingly n-l-S is the minimum number of storing relays which may be employed under these conditions.

When the direction of transmission through'the repeating station is reversed so as to cause signal impulses originating at the remote terminal section 2 to be repeated to section I, the conditions will be as indicated in Figs. 2 and 3. Referring to Fig. 2, the storing brush 6 will just have completed 'its Vtraverse of segment BX when sending brush? is about to traverse segment Ax. Fig. 3

shows that when the sending brush 'I has advanced to the position Where it has just com-` of storing relays required in transmitting from n the high speed section to the low speed section .is

greater, that is, R2=(1z+2)r+l.

equal to the spacing of the storing and restoring brushes plus 1 provided that the number of 'segments in a group of A segments is not less than that spacing. lThis relation is expressed by the equation R1=nl3, where R1 is the number of storage relays required to repeat from the high Y speed section to the low speed section. If the brush spacing between the storing and restoring -brushes is more than sufficient to encompass the number of segments in an A group, the minimum permissibleV number of storage relays may be decreased by the minimum number of C segments that may be found between Vthe storing and restoring brushes at any instant during a distributor revolution. that special caseV Rlzn-I-S-l,

Where :r is the minimum number of C segments which is at any time included between the storingV and restoring brushes. I

It has been demonstrated that in transmitting from the lowspeed'section to the high speed section, the spacing between Vthe low speed distributor storing and restoring brushes must be n@ segments-l-two A segments, or n|2 in terms 25 of equal length A and C segments. In terms of the longer B segment, the spacingis (n-|-2)rv where r is the ratio between the length of an A segment and a B segment. R2 which should be employed in this case is one The foregoing formula hold also for the general case where the The number of relays` segment groups of the A ring may not be regular provided n represents the-maximum number of group C segments in any group on the distributor segments,

This solution may bring up another problem.

If, for example, a single channel is dropped oi Vand the segments corresponding to the ve dropped oi pulses are regularly distributed, the No. l pulse may foilow the No. 5 pulse of the previous character too closely to permit operation of the printer. This diniculty may be'overcome by adding to the local printer one or more storing relays which may hold incoming pulses and deliver them to the printer as soon as it is cleared` of the previously set up character.

In the case of a single'drop-o" channel it is also possible to separate the No. 5 and No. l segments from the drop-01T channel by a suliciently large interval to permit operation of the local printer without relay storing, the segments Nos. 2, 3 and 4 being located at approximately regular spacing between Nos. 1 and 5.A

The most unfavorable condition with respect tothe number of storing relays required for re-V peating channels results from grouping togetherk all ofthe drop-off impulses instead of distributing them uniformly in the'smallest possible group.

In this case n is for ordinary Baudet transmission live times the number of drop-oli channels and :every probably is zero.

Fig. 4 illustrates schematically a vdeveloped rotaryV distributor repeater and that part ofits accessory apparatus required for repeating four channels of a high speedsection I to a low speedk section 2.V The Vtwo drop-off channels operate local printers 9 and IB. y Section I is connected to deliver incoming impulses to a storing ring II with which are associated segments A1, A2, C1, C2, etc. Storing brush I2 which travels to the right as indicated,

distributes impulses received'from line sectionV I to segments A1 A2, C1, in turn. Associated With the A segments are four storage relays I3, I4, I5,

and 1 6 each o f whichis .cennectedio ene-.quarter of the A segments which .are equally spaced so that .every A segment lis lassociated -with one of the four storage relays. Relay I3 .which gis typicalv of the1four, .comprises an operating winding ,I 'I ,connected between segment A1 andground I8. Upon connection of ring `II to segment A1 by storing .brush I2, an impulse received from line section `I passes by way ofoperatng Winding I1 .to earthcausing the vwinding to energize and actuate its armatures I9 and 20. Armature I9 closes a holding circuit through the `operating winding by way of source 2|. Armature I9 also serves to connect the high ypotential terminal of source2 I -to -segment .A1 anditsfdirectly connected segment B1 of the low .speed distributor ring. Segment B1.according ly is maintained at a mark- ,ingor significant potential until armature I9 is released. A transmitting brush 23 carried E along with brush I2 by lthe 4moving element of the .distributor connects ring 22 and lowspeed section 2 in succession to segments B1, B2, etc. Accord- .inem as.brush..2.;3 traversed segment B1 it caused amarking or significant impulseto be transmitted .from segmentrto ring, 2 2. The duration of that transmitted impulse was v determined `by the lerigthof the transmittingsegmentlsothat the impulsesreceived from high s peedsection I are eiectively lengthened vbefore retransmission to section .2.

rA clearing or restoring ring ,24 VVto which a grounded source of current 25. isconnect ed isassociated with a series-of clearingpr restoring seg- `ments 26 corresponding in length and number to the A segments. A restoring brush V21 successively applies restoring potential to segments 26 from source 25. Restoring winding 28 connected betweenground I8 and lsegments 2 6 operates,

.discharged to earth and restored or, made ready YVtoa-receive a new charge.

Armatures I9 and ,2,9 after deenergization of the clearing or restoring winding 28 return to a central'position to which they are normally biased.

If at the instant the storing brush engages segment A1 no marking impulse is received, storage relay winding II remains unenergized and no marking potential is applied to segment B1. The drop-off channel segments C1,.etc.,. n general require no storing relaysince impulses received by them may be transmitteddirectly to the Alocal printer. Two such printers 9 and Ihave their respective electromagnets 30 each connected directly to segments C1, C2, etc. The corresponding segment 26 of the restoring ring is an inactive `segment-.winch merelyoccupies the otherwise vacantspace on the distributor ring.

In order that the four storage relays I3 to I6 inclusive, mayserve all of the A and B segments, the segments are movable together so that A1 is connected directlyv to A5, A9, etc., and A2 is likewise connected to Ae, A10, etc. It is, of course, understood that if segments A1 and B1, f or example, are charged to marking potential as a result otanimpulse received from the line section I, they will both be cleared and their associated storing relay I3 will be in normal position ready to operate anew when the storing brush I2 reaches contact A5 with which the same relay I3 is associated. In this manner it is vpossible .to store and repeat impulses from a Arelatively large number of `segments without requiring Aaninordinate numberof relays. Y v

When transmission is to be reversed in dir ection, that is, to take place from low speed section 2 toward high speed section I, it is necessary to reverse the connection with the repeater station. This may Abe accomplished in the general manner outlined in U. S. patent to A. M. Curtis, No. 1,632,2745, issued June 14, 1927. The direction reversing mechanism forms no part of the present invention and it is accordingly not illustrated. The circuit connections for transmission Ain the kreverse direction, that is, `from section 2 to section I, are illustrated in Fig. 5.

Referring to Fig. 5, line section 2 is shown connected for repeating four through channels to section I by means of apparatus comprising storing ring 3|, storing brush 32, storing segments YB1,B2, B3, etc., storing relays 33, 3d, 35 and 3 6, transmitting segments A1, A2, etc., transmitting brush-31 and transmitting ring 38. Interpolated betweenthe A segments are the segments C1, etc., which are associated with the printing transmitters 39 and 40 of the two drop-off channels. Inasmuch as the repeating operation is performed in the same manner as that of the circuit of Fig. 4, no additional explanation or" it is necessary.

Fig. 6 discloses a portion of the rotary distributorrepeater at a repeating station at which only a single drop-off channel is terminated. In that impulse of one code character and the No. 1 l

impulse of the succeeding character in order to allow suillcient time for the printing operation. The gure shows only the single channel dropoff receiver and the apparatus associated therewith. The through channel apparatus is similar to that of Fig. 4.

The distinctive feature of the repeater of this figure is the local distributor ring which comprises the two similar segmented rings 4I and 42 with their brush 43 which travels together with the other brushes of the distributor in well-known manner.

vThe rst two drop-off channel segments C1, Cz

.are each connected with an individual local storf ing relay to permit the rst two impulses of each codecharacter to be stored until after the printing opeartion of the previous code characterhas been completed. Segment C1 is connected to storing relay 44 which, when energized, locks upto hold a marking potential on segment 45 of the' llocal distributor ring. Similarly, segment C2 comaining three segments of the local drop-off y channel C3, C4 and C5 are each directly con- .nected with a selector magnet 11.8 of the local .printer .49. The local distributor rings 4I and 42 are provided with long printing segments and 5I, respectively. Segment 53 is connected to ground and segment 5I is connected to printing magnet 52 in a path through source 53 to ground.

Accordingly, as brush 23 sweeps into contact with segments 5B and 5I it closes the circuit of the printing magnet52 and causes a printing operarived at segments C1 and C2 are stored on seg- 75 restore segment 45.

, of relay 46 is connected in parallel with the Yrestoring Vwinding of vrelay 44 and is simul- Y taneously operated therewith to interrupt Vthe locking circuit of its own energizing relay and to discharge its associated local distributor ring segment 41; It will accordingly be apparent that this apparatus enables the drop-01T channel segments to be uniformly distributed around the face of the distributor while at the same time permitting ample time for the printing operation Yafter the code impulses have been received and set up to determine the character which is to be printed. Y

What is claimed is: l. Inccmbination, twomulti-channel trans- V mission lines ci unequal channel capacities, tervminal means connected to each line for operatingits respective line at full channel capacity,

and a multi-channel repeater connecting said lines for transmission in either direction over the two lines operating as a unit.

2. In combination, two transmission lines of unequal channel capacities having a terminal of one line adjacent a terminal oi the other, transmitting means connected to eachV line for transfifi mitting impulses thereover up to the full capacity of the respectively associated line and automatic repeating kmeans connecting said lines for causing two way repetition therebetween of impulses ycorresponding to the full channel capacity oi the lower capacity line.

3. In combination,V two line sections, a rotary distributonmeans comprising circuits connecting the adjacent terminals of said sections. to divide the total line time of one section equally into'a plural number of channels and to divide the total ,line time of the other section equally into a different plural number of channels, whereby the circuits provide through transmission over both sections for the' smaller number of channels and :means for diverting at the repeaterthe remaining channels of the higher number.

.4. In combination, two transmissionV lines,Y

multi-channel transmittingand receiving means connected to one of said lines for causing multipleX y transmission thereover, Ymulti-channel transmitting and receiving means connected toYV said second line, said second mentioned means v having aV dierent number of channels from said iirst mentioned means and means interconnecting adjacent terminals ci said two lines for causing through transmission on a plurality of channels over the two lines operating as a single line of their combined length.

5. VA transmission line, multiplex channel terminal apparatus comprising a rotary distributor connected to said line, said distributor serving to divide the time of said line into a number of Y channels, a separate transmission circuit, means for enabling transmission of impulses thereovei, and a second transmission line havingfrotary distributor multiplex terminal apparatus of a number of channels equal to the combinedr number of channels of said rst line and of said separate circuit, and means connecting a terminal of said second line withsaid first line'and said separate circuit for causing the entire transmission thereof to be transmitted over said'second circuit.

6. In combination, a transmission line, signal transmitting means Vconnected to said line for dividingthe time of said line Vinto a number of sequentially occurring channels of equal duration, a second transmission line, signal transmitting means connected to said second line for dividing theA time of said second line into a number of equal sequentially occurring channels of Ya duration different from that of the channels of said rst-mentioned line, and automatic repeater means interconnecting said lines for causing electrical impulse repetition between channels of said lines. -f

'7. In combination, a low speed line section,-a

high speedline section having a terminal adja.-

' cent the terminal of said low speed section, automatic repeater means connecting said sections for causing the full message capacity of said low speed section to be transferred to orV from said high speed section, and means for diverting the remaining message capacity of said high speed section whereby both sections may be continuously worked at full capacity. Y

8. In combination, a low speed line section, a high speed line section, a rotary repeaterY connecting said sections and means connected to said 9 repeater for causing the through transfer Vto and from said high speed section of the additional message capacity thereof not utilized by said low speed section, said means comprising storage devices whereby the message impulses from onev section may be stored and repeated at the proper times to the other section.

9. A transmission line, means connected thereto for dividing the operation time of said line into a number of sequentially occurring channels, a second transmission line, means for dividing the operation time of the second line into a larger number of sequentially occurring channelsfthan that of said rst line, means for repeating impulses irom certain channels of said ,iirst vline to corresponding channels ofV said second line,

said means comprising groups of storage elements, means in each group for repeating the impulses stored in it by one line to a vsecond line, the number of said groups being less than the number of channels repeated thereby.

10. A repeating station, a plurality of transmission lines terminating thereat` and having unequal message transmitting capacities, said station comprising rotary distributor means for di- YcoY viding the line times of said transmission lines Y each into a number ofV channels individual to the respective line, means for transmitting messages over each of said lines and capable of operating Veach line at its full message capacity, and means connected to said lines and said rotary distributor means for transmittingrthrough said repeater station from one of said lines messages corresponding to the full message capacity of saidY line.

- EVERETT T. BURTON. 

